GN14: Branch Junctions: A Classification System for Arborists
A logical, accessible approach to classification and identification
There are many common terms currently in use as descriptions of the location where two or more branches or stems of a tree are conjoined, or where a branch is conjoined to a stem: e.g., attachment, bifurcation, fork, junction, union and other terms are all regularly applied to the same feature (or very similar features) of a tree’s anatomy. Additionally, the location between the two conjoined members is often referred to as the axil or crotch. Added to this, there are also a range of terms used when bark is included in such a junction, e.g., bark inclusion, compression fork, tight union, v-fork.
Given the importance of accurate communication concerning tree structures in tree-related reports, scientific work and for risk management purposes, this Guidance Note provides an evidence-based framework for the description of branch junctions in the many different forms in which they can be found.
There are three levels of description prescribed in this Guidance Note (simple, detailed and advanced; see section 5) so that users of this classification system can choose the level of detail that needs to be recorded or reported. Where this Guidance Note refers to a ‘detailed description’, this term is used to refer to the detailed and advanced descriptions of branch junctions, in contrast with a simple description. Only since 2016 has there been published evidence that a phenomenon known as ‘natural bracing’ can greatly influence the structural development and strength of branch junctions, so this guide is the first to incorporate that consideration within the reporting of tree structures.
Overall, it is hoped this document is helpful in achieving a common language that can be used when reporting or discussing branch junctions in trees, for arborists, arboriculturists and other interested professionals. The language and terminology used are intended to be both logical and accessible.